1. Field of the Invention
The present invention relates to a session based service, and more particularly, to a method and terminal for establishing a PT session in order to allow a certain user to use a PT box service under a control of a PT server in a SIP (Session Initiation Protocol) based service.
2. Discussion of the Related Art
In general, SIP denotes a signaling protocol which defines a procedure in which terminals desiring to communicate each other identify and find their locations, and establish or release (or change) multimedia service sessions therebetween. Services based on the SIP (i.e., SIP based services) have a request/response structure of controlling generation, modification and termination of multimedia service sessions. Also, the SIP based services provide services by using a SIP Uniform Resource Locator (URL), which is similar to an email address, without regard to IP (Internet Protocol) addresses so as to enable identification of each user.
A Push-To (PT) service may be one of the SIP based session services. The PT service is intended to provide rapid communications for service providers and mobile communication users. Also, the PT service is a type of half duplex communication service, namely, a communication service in which one client transmits media data (e.g., talk burst or media burst) to one or more other clients with which a session has been established. The PT service can typically be a Push-to-talk Over Cellular (PoC) service for transmission of voice (audio) data, a Push-To-View (PTV) service for transmission of moving picture (video) data, or a Push-To-Data (PTD) service for transmission of data.
The PT service provides a peer-to-peer (1-to-1) communication as well as a peer-to-group communication as in a group chat session (1-to-many), and uses a Session Initiation Protocol (SIP) to establish a session.
FIG. 1 is a signal flowchart illustrating a method for using a PT service according to a related art.
It is assumed in FIG. 1 that a PT client A equipped with a particular terminal (or PT User Equipment (UE)) denotes an entity for processing SIP messages, and messages shown in FIG. 1 are all SIP based messages.
In order to use the related art PT service, several preconditions first need to be satisfied, namely, the particular terminal should be registered in a SIP/IP core and a PT service setting should be done in a PT server.
As illustrated in FIG. 1, a PT client A 15 registers in a SIP/IP core A 20 (e.g., 3GPP IMS or 3GPP2 MMD) using a SIP REGISTER message (S1). The SIP/IP core A 20 sends a SIP 200 OK message to the PT client A 15 to inform that the PT client A 15 has successfully been registered in the SIP/IP core A 20 (S2).
The PT client A 15 delivers set values required for the PT service (i.e., PT service setting) to a PT server A 30 via the SIP/IP core A 20 by using a SIP PUBLISH message, where the PT service setting values include, for example, answer mode information, incoming session barring flag, instant personal alert barring flag, simultaneous support flag, etc. (S3 and S4). Here, the PT service setting values are delivered by being included in a body of the SIP PUBLISH message.
The PT server A 30 stores the PT service setting values therein (S5). The PT server A 30 also informs the PT client A 15, by using the SIP 200 OK message, that the PT service setting values have successfully been stored (S6 and S7). Here, in steps S6 and S7, the SIP 200 OK message is delivered from the PT server 30 to the PT client A 15 via the SIP/IP core A 20.
The aforementioned steps S1 and S2 are referred to as a ‘registration’ process, and steps S3 to S7 are referred to as a ‘PT service setting’. Although there may be various PT services available, there is no PT box service available to the terminal according to the related art. Thus there is a need to provide a technique of providing a PT box service to the terminal. A PT box service would provide a media data box (PT box) to which media data (e.g., voice messages, images, data, etc.) directed to a user of the PT terminal can be forwarded and stored, e.g., when the user is not available, so that the user can later access the PT box to obtain the stored media data therefrom.